A lubricant may be a liquid, a paste, or a solid with liquid lubricants being the most used. Lubricating oils may be used in automobile engines, transmissions, bearings, gears, industrial gears and other machinery to reduce friction and wear and to increase fuel economy. A number of components including, but not limited to dispersants, detergents, friction modifiers, antiwear agents, antioxidants, and anti-corrosion additives are typically present in fully formulated lubricating oils. For many lubricant applications, a viscosity index improver may also be included as a major component.
With the energy resources depleting and more stringent environmental regulations being adopted, there exists a greater demand to increase a fuel economy of vehicles and to decrease emissions in vehicle exhausts. Currently, organic friction modifiers are added to the lubricating oils to increase fuel economy. However, the level of the fuel economy achievable by organic friction modifiers is limited. Hence, there is a need for alternate methods for achieving improvements in fuel economy.
One method for increasing fuel economy is to provide lower viscosity grade lubricating oils. While providing lower viscosity lubricating oils may dramatically increase fuel economy, such lubricating oils may also increase wear. Wear may be partially reduced by using antiwear agents such as zinc dialkyldithiolphosphate (ZDTP). However, ZDTP contains phosphorus and its decomposition products may have deleterious effects on automotive catalyst systems for emission control. Accordingly, there remains an increasing need for methods for reducing friction and wear without adversely affecting emission control systems and without further depleting scarce natural resources.
With regard to the above, exemplary embodiments described herein provide methods for reducing friction coefficients and wear between lubricated surfaces. The method includes providing an amount of an oil-soluble nanospherical component derived from a photo-crosslinkable poly(2-cinnamoyloxyalkyl acrylate) core and a diblock acrylate copolymer corona in a fully formulated lubricant composition containing a base oil of lubricating viscosity. The nanospherical component has a core diameter ranging from about 10 to about 100 nanometers. According to the method, the lubricant composition containing the nanospherical component is applied to a surface to be lubricated.
In another embodiment, there is provided a method of reducing a friction coefficient of an engine lubricant composition during operation of an engine containing the lubricant composition. The method includes contacting the engine parts with a fully formulated lubricant composition having a base oil of lubricating viscosity and an amount of an oil-soluble nanospherical component derived from a photo-crosslinkable poly(2-cinnamoyloxyalkyl acrylate) core and a diblock acrylate copolymer corona sufficient to reduce the friction coefficient to below a friction coefficient of a lubricant composition devoid of the oil-soluble nanopherical component. The nanospherical component has a core diameter ranging from about 10 to about 100 nanometers.
A further embodiment of the disclosure provides a method for reducing wear between moving parts using a lubricating oil. The method includes using as the lubricating oil for one or more moving parts a lubricant composition containing a base oil, and an oil additive package including a wear reducing agent. The wear reducing agent is an oil-soluble nanospherical component derived from a photo-crosslinkable poly(2-cinnamoyloxyalkyl acrylate) core and a diblock acrylate copolymer corona.
A further embodiment of the disclosure provides a method for reducing a friction coefficient adjacent a lubricated surface, comprising providing an amount of an oil-soluble nanospherical component derived from a photo-crosslinkable poly(2-cinnamoyloxyalkyl acrylate) core and a diblock acrylate copolymer corona in a fully formulated lubricant composition containing a base oil of lubricating viscosity, and applying the lubricant composition containing the nanospherical component to a surface to be lubricated, wherein the nanospherical component has a core diameter greater than the film thickness of the lubricant composition.
A further embodiment of the disclosure provides a method of reducing a friction coefficient of an engine lubricant composition during operation of an engine containing the lubricant composition, comprising contacting the engine parts with a fully formulated lubricant composition comprising a base oil of lubricating viscosity and an amount of an oil-soluble nanospherical component derived from a photo-crosslinkable poly(2-cinnamoyloxyalkyl acrylate) core and a diblock acrylate copolymer corona sufficient to reduce the friction coefficient to below a friction coefficient of a lubricant composition devoid of the oil-soluble nanospherical component, wherein the nanospherical component has a core diameter greater than the film thickness of the lubricant composition.
As set forth briefly above, embodiments of the disclosure provide unique finished lubricant compositions that may significantly improve the coefficient of friction of the lubricant composition and may reduce wear for relatively low viscosity lubricant compositions. An additive package containing the oil-soluble nanospherical component may be mixed with an oleaginous fluid that is applied to a surface between moving parts. In other applications, an additive package containing the oil-soluble nanospherical component may be provided in a fully formulated lubricant composition.
The methods described herein are particularly suitable for reducing contamination of pollution control devices on motor vehicles or, in the alternative, the compositions are suitable for improving the friction coefficient characteristics and wear properties of lubricant formulations. Unlike fullerenes and inorganic nanoparticles, the nanospherical components described herein enable better particle size and shape control, which may be beneficial for enhancing lubricant effectiveness. Other features and advantages of the methods described herein may be evident by reference to the following detailed description which is intended to exemplify aspects of the exemplary embodiments without intending to limit the embodiments described herein.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the embodiments disclosed and claimed.